Zinc citrate beads in oral compositions

ABSTRACT

An anti-tartar oral product is provided which includes from about 0.001 to about 20% of beads which include a zinc salt and a gum held in a water matrix, the zinc salt and gum being present in a relative weight ratio from about 10,000:1 to about 10:1, and a dental base.

SUMMARY OF THE INVENTION

An anti-tartar oral product is provided comprising:

(i) from about 0.001% to about 20% of beads which include a zinc saltand a gum held in a water matrix, the zinc salt and gum being present ina relative weight ratio from about 10,000:1 to about 10:1; and

(ii) a dental base.

DETAILED DESCRIPTION OF THE INVENTION

Now it has been found that the bitter taste of zinc salts can beimproved by complexing the zinc salt with a gum to form active beads. Onan equal zinc salt weight basis, the beads are at least as effective inanti-tartar activity as solubilized or dispersed non-complexed zincsalts of the known art.

Zinc salts usable for the present invention may include inorganic ororganic counterions. Organic counterions include C₂-C₂₀ compounds,especially carboxylates. Preferred organic counterions include citrates,malates, malonates, maleates, adipates, succinates, acetates,propionates, lactates, tartrates, glycolates and combinations thereof.Most especially preferred is zinc citrate trihydrate.

Inorganic zinc salts are less preferred than the organic ones. Theseinclude counterions such as halides (e.g. chloride, bromide and iodide),sulfates, nitrates, phosphates and combinations thereof.

Amount of the beads may range from about 0.01 to about 20%, preferablyfrom about 0.5 to about 10%, optimally from about 1 to about 5% byweight of the total oral product.

A gum is a second essential component of the beads according to thepresent invention. Illustrative gums are polysaccharides includingsodium carboxymethyl cellulose (CMC), hydroxyethylcellulose,methylcellulose, ethylcellulose, hydroxypropyl cellulose, hydroxypropylmethylcellulose, gum tragacanth, gum arabic, gum karaya, pectin,carageenan, guar, xanthan gum, starch and combinations thereof. Mostpreferred are the cellulose type gums, especially sodium carboxymethylcellulose (CMC). All molecular weight types of sodium CMC may be useful,although the medium viscosity grade such as the 9M grade is mostsuitable.

Beads of the present invention are formed by the complexation of thezinc salt with the gum in the presence of water to form gel particles.Relative weight ratios of the zinc salt to gum in the beads may rangefrom about 10,000:1 to about 10:1, preferably from about 1,000:1 toabout 100:1 by weight.

Relative weight ratios of the zinc salt to water in the beads may rangefrom about 50:1 to about 1:50, preferably from about 20:1 to about 1:1,optimally from about 10:1 to about 6:1 by weight.

Typically the amount of zinc salt in the beads may range from about 1 toabout 99%, preferably from about 15 to about 98%, more preferably fromabout 50 to about 95%, optimally from about 75 to about 90% by weight ofthe beads. Amounts of the gum within the bead may range from about 0.001to about 2%, preferably from about 0.1 to about 1%, optimally from about0.25 to about 0.5% by weight of the beads. The remainder of the beadcomposition generally is water present in amounts from about 1 to about60%, preferably from about 2 to about 40%, optimally from about 5 toabout 20% by weight of the beads.

Average particle size of the beads may range from about 0.01 to about50, preferably from about 0.1 to about 10, optimally from about 0.3 toabout 5 micron. Bulk density of the beads may range from about 0.75 toabout 0.95, preferably from about 0.8 to about 0.9, optimally from about0.81 to about 0.84 gm/cc.

Beads according to the present invention are prepared prior tointroduction into a dental base with other ingredients of the oralproduct. Zinc salt, gum and water can be formed by mixing in a Hobarttype blending apparatus.

In one embodiment, the beads are visually distinct in the dental base.This may be accomplished by the beads being opaque and the base beingtransparent. Alternatively, the beads may appear as clear bodies coloreddifferently from a transparent or opaque base.

Besides the beads, the oral product will contain a dental base in anamount of about 80 to about 99% by weight. Ingredients of the dentalbase may include humectants, thickeners, abrasives, anti-caries agents,surfactants, colorants, flavorants, opacifiers, water and a variety ofspecial actives (e.g. desensitization agents such as potassium nitrate,peroxides and anti-bacterials such as triclosan).

Surfactants useful herein may be of the anionic, nonionic, cationic,zwitterionic or amphoteric type. Most preferred are sodium laurylsulphate, sodium dodecylbenzene sulfonate and sodium lauryl sarcosinate.Amounts of the surfactant may range from about 0.5 to about 10%,preferably from about 1 to about 5% by weight of the dental base.

Humectants useful herein are usually polyols. Illustrative of thiscategory are sorbitol, maltitol, mannitol, glycerin, propylene glycol,xylitol, hydrogenated corn syrup, polyethylene glycols and mixturesthereof. Amounts of the humectant may range from about 1 to about 60%,preferably from about 5 to about 50%, optimally from about 10 to about40% by weight of the dental base.

Thickeners useful herein may be the same gums as utilized to complexwith the zinc salts. However, these gums will be formulated into thedental base rather than into the pre-formed beads. Illustrativethickeners include sodium carboxymethyl cellulose, ethylcellulose,carageenan, xanthan gum, pectin, chemically modified starches andacrylates. The latter may be crosslinked polyacrylates such as Carbopol®934. Inorganic thickeners are exemplified by silica aerogels andmagnesium aluminum silicate, commercially available as Veegum®. Amountsof the thickener may range from about 0.01 to about 30%, preferably fromabout 0.1 to about 20%, optimally from about 0.5 to about 5% by weightof the dental base.

A fluoride anti-caries compound normally is usually present as part ofthe dental base. Illustrative of such fluoride compounds are sodiumfluoride, potassium fluoride, calcium fluoride, stannous fluoride,stannous monofluorophosphate, sodium monofluorophosphate and copperfluoride. Most preferred is sodium fluoride. These sources shouldrelease anywhere from about 25 to about 5,000 ppm of fluoride ion. Theanti-caries compound will normally be present in an amount from about0.01 to about 5%, preferably from about 0.1 to about 2.5%, optimallyfrom about 0.2 to about 1.5% by weight of the dental base.

Abrasives may also present in the dental base. Illustrative materialsinclude sodium metaphosphate, dicalcium phosphate, calciumpyrophosphate, silica, alumina, chalk, insoluble bicarbonate salts andmixtures thereof. Amounts of the abrasive may range from about 1 toabout 80%, preferably from about 5 to about 50% by weight of the dentalbase.

When the oral compositions are gels, structurants may be necessary.Particularly useful as a structurant arepolyoxyethylene-polyoxypropylene copolymers such as those sold under thetrademark Pluronic®. These materials are also known as Poloxamers andemployed in amounts from about 5 to about 30%, preferably from about 18to about 25% by weight of the dental base.

Flavors may also be part of the dental base. These flavors may be basedon oils of spearmint and peppermint. Examples of other flavoringmaterials include menthol, clove, wintergreen, eucalyptus and aniseed.Flavors may range in amount from about 0.1 to about 5% by weight of thedental base.

Sweetening agents may also be included in the dental base. Illustrativeagents include saccharin, sodium cyclamate, aspartame, acesulfame,xylitol and combinations thereof at levels from about 0.1 to about 10%by weight of the dental base.

Other additives may also be incorporated into the dental base. These maybe anti-tartar agents, colorants, preservatives, silicones, othersynthetic or natural polymers such as Gantrez S97®, and mixturesthereof. Amounts of these other ingredients may range from about 0.01 toabout 20% by weight of the dental base.

Water may be present in the dental base in amounts from about 1 to about95%, preferably from about 20 to about 60%, optimally from about 30 toabout 50% by weight of the dental base.

Except in the operating and comparative examples, or where otherwiseexplicitly indicated, all numbers in this description indicating amountsof material ought to be understood as modified by the word “about”.

The term “comprising” is meant not to be limiting to any subsequentlystated elements but rather to encompass non-specified elements of majoror minor functional importance. In other words the listed steps,elements or options need not be exhaustive. Whenever the words“including” or “having” are used, these terms are meant to be equivalentto “comprising” as defined above.

The following examples will more fully illustrate the embodiments ofthis invention. All parts, percentages and proportions referred toherein and in the appended claims are by weight unless otherwiseillustrated.

EXAMPLE 1

Zinc salt beads of the present invention were prepared in severaldifferent ways. One procedure utilized a Hobart bowl. Zinc citrate wasadded to the bowl and a 2% CMC solution was slowly added with mixinguntil the beads formed. They were then air dried and sieved. A secondmethod for preparation was via a ribbon blender, again adding a 2%solution of CMC to the dry zinc citrate.

Fluidized bed technology can also be utilized for manufacture of thebeads. By this procedure zinc citrate was suspended in the fluid bedreactor while a nozzle sprayed a 2% solution of CMC. The spray drierutilized for this purpose was a GPCG-5, ex Glatt Technologies with aSchlick 924 nozzle. This model was able to produce 5-7 kilogram batches.The 2% CMC solution was sprayed using a peristaltic pump along withpressurized air at the nozzle to atomize the spray. Achievement ofoptimum results required swift introduction of the CMC, use of cool airto fluidize, and maintenance of the product temperature during drying sothat it stayed below 40° C. The relatively cool air prevented solidsfrom sticking together before the beads were formed. During drying, thetemperature quickly rose after water was removed. Care was taken not toover-dry which could lead to a frail bead. When the temperature reached35° C., the batch was considered dried.

EXAMPLE 2

A typical gel dentifrice composition incorporating the beads of thisinvention is described below.

TABLE I Component Weight % Sorbitol 56.33 Syloid 63X ® 10.0 Syloid 244 ®9.0 Polyethylene glycol (1500 M.W.) 5.00 Ethyl alcohol 2.1 Sodium laurylsulfate 1.6 Menthol 1.0 Sodium monofluorophosphate 0.8 Cellulose gum 0.4Sodium saccharin 0.3 Beads (Zinc Citrate/CMC in 200/1 ratio) 0.5 WaterBalance

EXAMPLE 3

An opaque toothpaste with the beads of this invention has a formula asdescribed below.

TABLE II Component Weight % Sorbitol 15.0 Glycerin 3.0 Calcium phosphatedihydrate, dibasic 33.5 Anhydrous calcium phosphate, dibasic 5.0Titanium dioxide 1.5 Sodium lauryl phosphate 1.5 Carboxymethyl cellulose1.2 Sodium monofluorophosphate 0.8 Peppermint oil 0.6 Sodium saccharin0.4 Beads (Zinc Citrate/CMC in 300/1 ratio) 1.0 Water Balance

A comparative taste test is reported under this Example. Two formulaswere evaluated. The first was according to Example 2 wherein zinccitrate was present in the form of complexed insoluble beads. Acomparative experiment utilized the same formula as in Example 2 exceptthat an equivalent amount of zinc citrate was solubilized within theformula rather than present as insoluble beads.

A flavor tasting panel was assembled consisting of thirteen persons.They rated the zinc citrate bead and the non-bead solubilized toothpasteafter brushing, according to a series of organoleptic attributes.Ratings were on a scale of 1 to 5, where 1=poor and 5=excellent. Afterbrushing with both products, the panelists chose their preference. TableIII below lists results of the flavor test. Values provided in thesecond and third column are average ratings except for the “preference”entry where 9 people chose the bead product, 3 people chose the control(zinc citrate solubilized) and 1 person had no preference.

TABLE III Flavor Test ZINC CITRATE SENSORY PERCEPTION ZINC CITRATE BEADSSOLUBILIZED Flavor 4.00 3.31 Strength 3.92 3.77 Foam 3.38 3.54 AfterTaste 3.46 2.92 Feel Clean 4.00 3.69 Impact 3.92 3.38 Overall Liking3.85 3.31 Preference 9.00 3.00

The tests indicate that the zinc citrate in bead form was favored in sixof the seven taste categories. Only foam was found to be better in thecomparative formula. The overall preference, by a wide margin, was forzinc citrate in the bead form rather than solubilized.

The foregoing description and examples illustrate selected embodimentsof the present invention. In light thereof variations and modificationswill be suggested to one skilled in the art, all of which are within thespirit and purview of this invention.

What is claimed is:
 1. An anti-tartar oral composition comprising: (i)from about 0.001% to about 20% of beads comprising a zinc salt and a gumheld in a water matrix, the zinc salt and gum being present in arelative weight ratio from about 10,000:1 to about 10:1; and (ii) adental base.
 2. The composition according to claim 1 wherein the zincsalt is zinc citrate trihydrate.
 3. The composition according to claim 1wherein the gum is a cellulose.
 4. The composition according to claim 1wherein the gum is sodium carboxymethyl cellulose.
 5. The compositionaccording to claim 1 wherein the ratio of zinc salt to gum ranges fromabout 1,000:1 to about 100:1.
 6. The composition according to claim 1wherein the dental base comprises a material selected from the groupconsisting of humectants, thickeners, surfactants, colorants,flavorants, anti-caries agent, abrasives, opacifiers, water andcombinations thereof.
 7. The composition according to claim 1 whereinthe beads are pre-formed and then combined into the dental base.
 8. Thecomposition according to claim 1 wherein the beads are opaque and thedental base is transparent.
 9. An anti-tartar oral compositioncomprising: (i) from about 0.001% to about 20% of beads comprising azinc salt and a gum held in a water matrix, the zinc salt and gum beingpresent in a relative weight ratio from about 10,000:1 to about 10:1;and (ii) a dental base, the beads being visually distinct from thedental base.
 10. Beads for use in oral compositions comprising a zincsalt complexed with a gum in water, the zinc salt to gum ranging inweight ratio from about 10,000:1 to about 100:1.
 11. The compositionaccording to claim 1 wherein the beads have a bulk density ranging fromabout 0.75 to about 0.95 gm/cc.
 12. The composition according to claim 1wherein the beads have a bulk density ranging from about 0.81 to about0.84 gm/cc.
 13. The composition according to claim 9 wherein the beadshave a bulk density ranging from about 0.75 to about 0.95 gm/cc.
 14. Thecomposition according to claim 9 wherein the beads have a bulk densityranging from about 0.81 to about 0.84 gm/cc.
 15. The beads according toclaim 10 wherein the beads have a bulk density ranging from about 0.75to about 0.95 gm/cc.
 16. The beads according to claim 10 wherein thebeads have a bulk density ranging from about 0.81 to about 0.84 gm/cc.